plugin(npm): make npm plugin public and create a standalone demo application

[karthikjeeyar]

This PR does the following

• standalone npm demo application.
• make npm plugin public

How to test:

1. navigate into the workspaces/npm/plugins/npm folder
2. run yarn start

:heavy_check_mark: Checklist

• [x] A changeset describing the change and affected packages. (more info)
• [ ] Added or updated documentation
• [ ] Tests for new functionality and regression tests for bug fixes
• [x] Screenshots attached (for UI changes)
• [x] All your commits have a Signed-off-by line in the message. (more info)